dyestuffs of the formula ##STR1## are provided wherein R1 is hydrogen, alkyl, substituted alkyl, aryl, substituted aryl, amino or substituted amino, amido or substituted amido or hydroxyl, alkoxy, thioalkoxy or a carboxyl group or an ester thereof, R2 represents either --N═ or a linking group ═CH--(CH═CH)n -where n is 0, 1 or 2 and R3 is an optionally substituted heteroaromatic ring which optionally may be benzannelated, an optionally substituted benzene ring, an optionally substituted 5- or 6-membered heterocyclic or carbocyclic ring, which contains at least one hydroxyl group and may optionally be benzannelated, or R3 is a group ##STR2## wherein n is 0, 1 or 2, V is an optionally substituted 5- or 6- membered heterocyclic or carbocyclic ring, and Q is a group of the formula ##STR3## where each of W and Y are hydrogen, optionally substituted alkyl, optionally substituted cycloalkyl or optionally substituted aryl or together they represent the atoms necessary to complete a 5- or 6 -membered ring system, and X is an anion.
The dyestuffs of the present invention are of use as dyes in photosensitive material which are not required to be present in the exposed and processed material. The dyestuffs of the present invention thus are useful as antihalation dyes, filter dyes and as acutance dyes.
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1. A dyestuff of the formula ##STR58## wherein, R1 is alkyl of 1 to 5 carbon atoms, amino, amido, hydroxyl or carboxyl, phenyl substituted by halogen, hydroxyl, alkyl or alkoxyl of 1 to 5 carbon atoms,
R2 is -N═ or ═CH-(CH═CH)n - where n is 0, 1 or 2 and R3 is 5-membered nitrogen-containing heterocyclic ring with 1 or 2 nitrogen atoms, a 6-membered nitrogen-containing heterocyclic ring with 1 nitrogen atom or these rings fused with a benzene ring, phenyl or phenyl substituted by halogen, hydroxyl, alkyl of 1 to 5 carbon atoms, carbalkoxyalkoxy with 1 to 5 carbon atoms in each alkoxy moiety or dialkylamino with 1 to 5 carbon atoms in each alkyl radical, R3 is further a heterocyclic ring of the formula ##STR59## wherein, V1 represents the atoms to complete a 5- or 6-membered nitrogen-containing heterocyclic ring with 1 or 2 nitrogen atoms or this ring substituted by hydroxyl, alkyl of 1 to 5 carbon atoms or cyano, and Q is a group of the formula ##STR60## wherein W1 and Y1 are hydrogen or alkyl of 1 to 5 carbon atoms and X is an anion.
2. A dyestuff according to
B is dialkylamino of 1 to 5 carbon atoms in each alkyl radical, Q is a group of the formula ##STR62## wherein, W1 and Y1 are hydrogen or alkyl of 1 to 4 carbon atoms and X is an anion and n is 0 or 1.
3. A dyestuff according to
4. A dyestuff according to
X is an anion, n is 0, 1 or 2 and the group ##STR69## is either a pyridone of the formula ##STR70## wherein, R6 and R7 are each alkyl groups of 1 to 5 carbon atoms or is a pyrazolone of the general formula ##STR71## where R1, Q and X have the indicated meanings.
5. A dyestuff according to
6. A dyestuff according to
M is dialkyl amino with 1 to 5 carbon atoms in each alkyl moiety.
7. A dyestuff according to
Q is a group of the formula ##STR77## wherein, W1 and Y1 are hydrogen or alkyl of 1 to 4 carbon atoms, X is an anion and the group ##STR78## is a pyridone group of the formula ##STR79## wherein, R6 and R7 are each alkyl groups of 1 to 5 carbon atoms.
8. Photographic material which comprises in at least one layer thereof a dyestuff according to
9. Photographic material according to
10. Photographic material according to
11. Photographic material according to
12. Photographic material according to
13. Photographic material according to
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This invention relates to novel pyrazolone dyestuffs and to their use in photographic materials.
According to the present invention there are provided new dyestuff of the formula ##STR4## where R1 is hydrogen, alkyl or substituted alkyl, aryl, substituted aryl, amino or substituted amino, amido or substituted amido, hydroxyl, alkoxy, thioalkoxy, carboxyl or carboxylester, R2 represents either --N═ or a linking group ═CH--(CH═CH)n -- where n is 0, 1 or 2 and R3 is an optionally substituted heteroaromatic ring which optionally may be benzannelated, optionally substituted benzene, an optionally substituted heterocyclic or carbocyclic ring of the formula ##STR5## where V represents the atoms necessary to complete an optionally substituted 5- or 6-membered heterocyclic or carbocyclic ring, which may optionally be benzannelated, or a group ##STR6## wherein n and V have the indicated meanings (n is preferably 0 or 1), Q is a group of the formula ##STR7## where each of W and Y are hydrogen, optionally substituted alkyl, optionally substituted cycloalkyl or optionally substituted aryl or together they represent the atoms necessary to complete a 5- or 6-membered ring system, and X is an anion.
Preferred are those dyestuffs of formula (1) wherein R1 is alkyl of 1 to 5 carbon atoms, phenyl or phenyl substituted by halogen, hydroxyl, alkyl or alkoxy of 1 to 5 carbon atoms, R2 is --N═ or ═CH--(CH═CH)n -- where n is 0, 1 or 2 and R3 is an optionally substituted 5- or 6-membered heterocyclic ring which may be optionally benzannelated, phenyl or phenyl substituted by halogen, hydroxy, alkyl of 1 to 5 carbon atoms, carbalkoxyalkoxy with 1 to 5 carbon atoms in each alkoxy moiety or dialkylamino with 1 to 5 carbon atoms in each alkyl radical, R3 is further a heterocyclic ring of the formula ##STR8## wherein V1 represents the atoms to complete a 5- or 6-membered heterocyclic ring which is optionally substituted by hydroxyl, alkyl of 1 to 5 carbon atoms or cyano, Q is a group of the formula ##STR9## wherein W1 and Y1 are hydrogen or alkyl of 1 to 4 carbon atoms aND X is an anion.
There may be one or more than one substituents attached to the ring system mentioned for R3. Most preferably W1 and Y1 are each hydrogen atoms. X is an anion of an organic or inorganic acid, such as fluoride, chloride, bromide, nitrate, hydrogensulfate, methylsulfate or acetate. The halides and nitrate are preferred.
The dyestuffs of formula (1) where R2 is --N═ are prepared by reacting a solution of a pyrazolone of formula ##STR10## where R1, Q and X have the indicated meanings with a nitroso compound of the formula R3 NO where R3 has the indicated meaning.
Similarly dyestuffs of formula (1) where R2 is ═CH(CH═CH)n -- are prepared by reacting a solution of pyrazolone of formula (4) with an aldehyde of the formula R3 --(CH═CH)n --CHO where R3 has the indicated meaning, or with an aldehyde derivative such as an acetal or anilino compound.
Preferably in the two processes the solvent for the pyrazolone is acetic acid.
The process may be carried out either at ambient or reflux temperatures.
The pyrazolones employed in this invention may be prepared by the methods of A. Vystrcil and R. Prokes, Chem. Listy, 1952, 46, 670 and of S. C. De and P. C. J. Rakshit, J. Indian Chem. Soc., 1936, 13, 509. In certain cases, for example where R1 is phenyl, 4-nitrophenyl, or amino, the intermediate hydrazone, rather than pyrazolone, is isolated from the reaction and is employed for dye synthesis, ring closure occuring in situ.
The preferred dyes of formula (1) are those of formula (5), (6), (7), (10), (12) and (13). ##STR11## where R1, Q, X and n have the indicated meanings and A, B and C are each hydrogen, halogen, hydroxy, alkoxy, thioalkoxy, optionally substituted alkyl, optionally substituted aryl, optionally substituted amino, optionally substituted amido or nitro, and D is hydrogen, or C and D together complete an optionally substituted aromatic or heterocyclic ring.
The especially preferred dyes of formula (5) are those wherein R1 is alkyl of 1 to 5 carbon atoms, phenyl or phenyl substituted by halogen, hydroxyl, alkyl or alkoxy of 1 to 5 carbon atoms. A, C, D are each hydrogen, halogen, hydroxy, alkyl of 1 to 5 carbon atoms or carbalkoxyalkoxy of 1 to 5 carbon atoms in each alkoxy moiety B is dialkylamino of 1 to 5 carbon atoms in each alkyl radical, Q is a group of the formula ##STR12## wherein W1 and Y1 are hydrogen or alkyl of 1 to 4 carbon atoms, X is an anion and n is 0 or 1.
Dyestuffs of formula ##STR13## where Z is a heteroaromatic ring which is optionally substituted and R1, Q, X and n have the indicated meanings.
Examples of preferred dyes of formula (6) are those wherein R1 is alkyl of 1 to 5 carbon atoms, phenyl or phenyl substituted by halogen, hydroxyl, alkyl or alkoxy of 1 to 5 carbon atoms, Q is a group of the formula ##STR14## wherein W1 and Y1 are hydrogen or alkyl of 1 to 4 carbon atoms, X is an anion, n is zero or 1 and Z is a group of the formula, ##STR15##
Dyestuffs of formula ##STR16## where R1, Q, X, V and n have the indicated meanings.
Preferred dyestuffs of formula (7) are those wherein R1 is alkyl of 1 to 5 carbon atoms and the group Q is a group of the formula ##STR17## wherein W1 and Y1 are hydrogen or alkyl of 1 to 4 carbon atoms, X is an anion, n is 0, 1 or 2 and the groups ##STR18## are pyridones of the general formula ##STR19## where R6 and R7 are each alkyl, preferably of 1 to 5 carbon atoms or pyrazolones of the general formula ##STR20## where R1, Q and X have the indicated meanings. The dyes of formula (9) are bispyrazolone oxonols.
Dyestuffs of formula ##STR21## where R1 Q, X, n and V have the indicated meanings. Particularly preferred groups ##STR22## are pyrrolines of general formula ##STR23## where R8, R9 and R10 are each alkyl or aryl, preferably alkyl of 1 to 5 carbon atoms or phenyl. Dyestuffs of formula ##STR24## where R1, Q and X have the indicated meanings and L is hydrogen, alkyl, alkoxy or optionally substituted amino and M is hydroxy, alkoxy or optionally substituted amino.
The especially preferred dyes of this class are those where M is dialkylamino of 1 to 5 carbon atoms in each alkyl radical, preferably methyl and L is hydrogen.
Dyestuffs of formula ##STR25## where R1, Q, X and V have the indicated meanings. Preferred dyestuffs of formula (13) are those wherein R1 is alkyl of 1 to 5 carbon atoms, preferably methyl, Q is a group of the formula ##STR26## wherein W1 and Y1 are hydrogen or alkyl of 1 to 4 carbon atoms, X is an anion and the group ##STR27## is the pyridone group of formula (8).
The dyestuffs of the present invention are of use as dyes in photosensitive material which are not required to be present in the exposed and processed material. The dyestuffs of the present invention thus are useful as antihalation dyes, filter dyes and as acutance dyes.
The dyestuffs of the present invention are useful in such functions because:
They are fully bleached by the processing procedure, especially by the sulphite in developer solutions, without subsequent regeneration of the dye in the photographic assembly.
They are easily formulated, in general being water-soluble. The majority of them displays controllable and beneficial aggregation in gelatin layers. This has the effects of
(a) increasing the visible spectral coverage of the dyes, owing to the emergence of absorption peaks ascribable to the aggregated species, and
(b) rendering the dyes excellently substantive in gelatin layers, without adversely affecting their bleachability.
In instances where aggregation (as adjudged by spectral coverages) does not occur (e.g. examples (115) and (118) below) substantivity is greatly reduced.
They possess the ability to mordant other anionic dyes, which are not of themselves very substantive in gelatin. An underlayer assembly containing one of the dyes of this invention and another anionic dye often displays absorption maxima which are not due to the presence of either dye singly in the layer, and may be between, or outside of, the absorption maxima normally displayed by the dyes in gelatin. The dyestuffs of the present invention show improved properties over those of e.g. British Patent Specification No. 506 385.
According to another aspect there is provided light-sensitive photographic material which comprises in at least one layer thereof a dyestuff of general formula (1).
The dyestuff of formula (1) may be present in a resin binder as an anti-halation backing layer on the reverse side of the film base to the photosensitive layer.
However, the dyestuff of formula (1) may be present in an anti-halation underlayer of the photographic material, that is to say between the film base and the lowest light-sensitive layer. The dyestuffs of formula (1) are of particular use in anti-halation underlayers because they are substantive to a coated gelatin layer which is the usual binder used in anti-halation underlayers and they are readily bleached by sulphite.
The dyestuffs of formula (1) are also of use as filter layers in colloid (usually gelatin) inter-layers between light sensitive layers.
Certain of the dyestuffs of formula (1) are also of use in blue-light filter layers placed above the topmost light sensitive layer in a photographic material.
The following Examples will serve to illustrate the invention.
PAC Dye synthesesIn these syntheses the following preformed pyrazolones of formula (4) are used:
| ______________________________________ |
| R1 Q X |
| ______________________________________ |
| Pyrazolone (101) |
| CH3 CN2 H3 |
| NO3 |
| Pyrazolone (102) |
| N-propyl CN2 H3 |
| NO3 |
| Pyrazolone (103) |
| p-CH3 OC6 H4 |
| CN2 H3 |
| NO3 |
| ______________________________________ |
Further the hydrazones of the formula ##STR28## are used. The latter one for the preparation of dye (119). Dye (106): Pyrazolone (101) (0.51 g) and indole-3-carboxaldehyde (0.36 g) were heated under reflux in acetic acid (2.5 ml) for ten minutes. The mixture was cooled, drowned in ether and the precipitate washed and dried. Yield=0.82 g, m.p. 226°-8°C
Dye (107): Essentially as for dye (106) employing instead pyrazolone (102) (0.58 g) and 4-dimethylaminobenzaldehyde (0.37 g). Yield=0.90 g, m.p. 203°-5°C
Dye (108): Essentially as for dye (107), employing instead hydrazone (104) (0.78 g). Yield=0.88 g, m.p. 172°-5°C
Dye (109): Essentially as for dye (108), employing instead 2-chloro 4-dimethylaminobenzaldehyde (0.51 g). Yield=1.04 g, m.p. 192°-3°C
Dye (110): Essentially as for dye (106), employing instead 4-diethylamino-2-ethoxycarbonylmethoxy benzaldehyde (0.70 g). Yield=0.95 g. Decomposes at 100°C
Dye (111): Essentially as for dye (106), employing instead pyrazolone (103) (0.74 g) and 1-phenylpyrrole-2-carbox-aldehyde (0.43 g). Yield=0.80 g, m.p. 166°-8°C
Dye (112): Essentially as for dye (108), employing instead 4-dimethylamino cinnamaldehyde (0.44 g). Yield=0.79 g, m.p. 125°-8°C
Dye (113): Pyrazolone (101) (0.51 g) and 3-cyano-5(5'-2"4"-dinitroanilinopenta-1,3-dienylino)-1-ethyl-6-hydroxy-4-m ethylpyrid-2-one (1.06 g) were stirred in acetic acid (10 ml) at ambient temperature for thirty minutes. The mixture was drowned in ether and the precipitate washed and dried. Yield=1.36 g, m.p. 202°-3°C
Dye (114): Essentially as for dye (108), employing instead 4-dimethylamino nitrosobenzene (0.42 g). Yield=1.02 g, decomposes at 120°C
Dye (115): Essentially as for dye (106), employing instead 3-cyano-1-ethyl-6-hydroxy-4-methyl-5-nitrosopyrid-2-one (0.52 g). Yield=0.85 g, decomposes at 250°C
Dye (116): Pyrazolone (101) (1.03 g) and 1,1,3,3-tetramethoxypropane (0.49 g) were heated under reflux in acetic acid (5 ml) for ten minutes. The mixture was cooled and drowned in ether, and the precipitate washed and dried. Yield=0.80 g, m.p. 219°-21°C
(117): Pyrazolone (101) (1.03 g) and glutaconic aldehyde mono-2',4'-dinitro anil (0.66 g) were stirred at ambient temperature in acetic acid (10 ml) for twenty minutes. The mixture was drowned in ether and the precipitate washed and dried. Yield=1.15 g, m.p. 218°-20°C
Dye (118): Pyrazolone (101) (1.03 g) and 2-(2"-acetanilidovinyl) 1-ethyl-3,3-dimethylpyrrolinium iodide (2.06 g) were heated under reflux in acetic acid (2.5 ml) for twenty minutes. The mixture was cooled and drowned in ether and the precipitated oil washed and reprecipitated from acetone into ether, to yield a red solid (1.11 g), m.p. 96°-97°C
Dye (119): Hydrazone (105) (0.44 g) and 1,1,3,3-tetramethoxypropane (0.15 g) were heated at reflux in acetic acid (2 ml) for 10 minutes. The cooled mixture was precipitated into ether, and reprecipitated twice from methanol into ether to give a gum (0.34 g).
The following table show the specific examples of dyes of formula (1) the manufacture of which is previously described.
| __________________________________________________________________________ |
| Dye No. |
| R1 R3 R2 Q X |
| __________________________________________________________________________ |
| (106) CH3 |
| ##STR29## CH |
| ##STR30## |
| NO3.crc |
| lbar. |
| (107) n-C3 H7 |
| ##STR31## CH |
| ##STR32## |
| NO3.crc |
| lbar. |
| (108) C6 H5 |
| ##STR33## CH |
| ##STR34## |
| NO3.crc |
| lbar. |
| (109) C6 H5 |
| ##STR35## CH |
| ##STR36## |
| NO3.crc |
| lbar. |
| (110) CH3 |
| ##STR37## CH |
| ##STR38## |
| NO3.crc |
| lbar. |
| (111) |
| ##STR39## |
| ##STR40## CH |
| ##STR41## |
| NO3.crc |
| lbar. |
| (112) C6 H5 |
| ##STR42## CH(CHCH) |
| ##STR43## |
| NO3.crc |
| lbar. |
| (113) CH3 |
| ##STR44## CH(CHCH)2 |
| ##STR45## |
| NO3- |
| (114) C6 H5 |
| ##STR46## N |
| ##STR47## |
| NO3.crc |
| lbar. |
| (115) CH3 |
| ##STR48## N |
| ##STR49## |
| NO3.crc |
| lbar. |
| (116) CH3 |
| ##STR50## CH(CHCH) |
| ##STR51## |
| NO3.crc |
| lbar. |
| (117) CH3 |
| ##STR52## CH(CHCH)2 |
| ##STR53## |
| NO3.crc |
| lbar. |
| (118) CH3 |
| ##STR54## CH |
| ##STR55## |
| NO3.crc |
| lbar. |
| (119) CH3 |
| ##STR56## CH(CHCH) |
| ##STR57## |
| Cl.crclbar. |
| __________________________________________________________________________ |
Dyed coated gelatin layers were prepared as follows:
| ______________________________________ |
| Stock Solutions |
| 6% Gelatin Gelatin 6 g |
| Distilled water |
| Swell at room temperature for 30 minutes and then |
| dissolve at 60°C Adjust to 40°C |
| Dyestuff 2.5 × 10-3 molar |
| Dissolve 0.25 mMol of the dyestuff in 10 ml water or |
| 2-ethoxy ethanol. Adjust solution to 40°C |
| Hardener 1% |
| Dissolve 100 mg of 1,3-dichlortriazine-5-aminobenzene-4- |
| sulfonic acid in 10 ml water. Adjust solution to 40°C |
| Wetting agent 5% neutral or anionic wetting agent |
| Coating solution |
| Gelatin stock solution |
| 3.5 ml |
| Distilled water 5.0 ml |
| Wetting agent(1) |
| 0.25 ml |
| Dyestuff 0.232 ml |
| Hardener 1.0 ml |
| ______________________________________ |
| (1) Diisobutylnaphthalenesulfonic-acid-sodium, 8% solution in |
| waterethanol 95:5. |
Coat at 40°C on plates affixed with triacetate base and allow to set for 5 minutes on a cold plate (≈10°C). Dry at room temperature.
| ______________________________________ |
| Gel coating weight 91.3 mg/dm2 |
| mMol Dye/100 g gel 2.76 |
| Dye coating weight 0.0025 mMol/dm2 |
| ______________________________________ |
Fourteen samples were prepared from dyes (106) to (119).
A 5 cm2 disc was cut and the visible spectrum measured. The disc was soaked in water (7.5 ml) for 30 minutes. The disc was allowed to dry and the spectrum measured again. ##EQU1##
A strip 2.5×7.5 cm was immersed 2.5 minutes in developer, 2 minutes in a fixing bath and washed 10 minutes in water before drying. ##EQU2##
The developer used comprised per 1000 ml, N-methylamino-p-phenolsulfate, sodium sulphite (anhydrous) 75 g, hydroquinone 8 g, sodium carbonate (anhydrous) 37.5 g and potassium bromide 2 g.
The fixer used comprised 82 g of ammonium thiosulphate per 1000 ml 2 g of.
The following results were obtained:
| ______________________________________ |
| Light absorption |
| Light absorption |
| maximum in maximum in Substant- |
| Bleach- |
| Dye methanol (nm) |
| gelatin (nm) ivity ability |
| ______________________________________ |
| (106) |
| 448 460, 435 100 95 |
| (107) |
| 504 518, 436 100 100 |
| (108) |
| 501 520, 456 99 95 |
| (109) |
| 500 563, 510, 465 |
| 100 96 |
| (110) |
| 497, 432 505, 484, 434 |
| 99 98 |
| (111) |
| 430 430 100 94 |
| (112) |
| 588 610, 486 100 96 |
| (113) |
| 648, 620, (sh) |
| 625, 473 96 100 |
| (114) |
| 565 580(sh), 535, 490(sh) |
| 446(sh) 86 100 |
| (115) |
| 560 568 7 100 |
| (116) |
| 517, 485(sh) 559, 522, 481, 432 |
| 91 98 |
| (117) |
| 613, 568(sh) 640, 474 93 100 |
| (118) |
| 416 418 11 98 |
| (119) |
| 519 506 12 100 |
| ______________________________________ |
| (sh) = shoulder |
(a) Stock solutions were made as follows:
Dye (107) 0.25 mMols in 10 ml H2 O
Dye (120) 0.25 mMols in 10 ml H2 O
(dye (120) is bis-(1-butyl-3-cyano-6-hydroxy-4-methylpyrid-2-one) trimethine oxonol triethylamine salt--Britisch Patent Specification No. 1,278,621).
The two stock solutions were used as follows to make a coating solution (other components were prepared as in Example 2):
| ______________________________________ |
| Gelatin stock solution 3.5 ml |
| Wetting agent 0.25 ml |
| Hardener 1.0 ml |
| Dye (107) solution 0.696 ml |
| Dye (120) solution 0.232 ml |
| Distilled water to 10 ml. |
| ______________________________________ |
The solution was coated and processed as in Example 2.
(b) as for (a), save that a solution of dye (108) (0.25 mMols in 10 ml water--0.232 ml) was used instead of the solution of dye (107).
(c) as for (a), save that dye (120) was coated alone (0.232 ml).
| ______________________________________ |
| Light absorption |
| Overall Overall |
| maxima in gelatin |
| substantivity |
| bleachability |
| Coating (nm) (%) (%) |
| ______________________________________ |
| (a) 440, 505, 552, 610 |
| 100 100 |
| (b) 437, 505, 610, 640 |
| 96 97 |
| (c) 608 44 99 |
| ______________________________________ |
This shows that the presence of either dye (107) or dye (108) increases the substantivity of dye (120), and that an absorption maximum not ascribable to the presence of either dye alone is generated.
| Patent | Priority | Assignee | Title |
| 4369310, | Nov 19 1979 | ILFORD LIMITED, A CO OF THE UNITED KINGDOM | Bleachable dyes |
| 4446227, | Feb 28 1980 | Ciba-Geigy AG | Dyestuffs and their use in photographic material |
| 5262284, | Jul 15 1991 | Eastman Kodak Company; EASTMAN KODAK COMPANY A CORP OF NEW JERSEY | Arylidene pyrazolone coupler |
| 5283165, | Dec 23 1992 | Eastman Kodak Company | Pyrrolinone dyes |
| 6518005, | Jul 07 2000 | PARCO TECNOLOGICO VAL BORMIDA S R L | Silver halide multilayer color photographic material |
| Patent | Priority | Assignee | Title |
| 3615546, | |||
| 3740228, | |||
| 3746539, | |||
| CH506094, | |||
| FR1240930, | |||
| GB506385, |
| Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
| Jan 22 1979 | Ciba-Geigy AG | (assignment on the face of the patent) | / | |||
| Apr 27 1982 | Ciba-Geigy AG | H A WHITTEN & CO P O BOX 1368, NEW YORK, NY 10008 A PARTNERSHIP | ASSIGNS ENTIRE INTEREST, SUBJECT TO LICENSE RECITED | 004005 | /0578 |
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